Yuga cycle

The Yuga cycle is the Hindu doctrine of four world ages: Satya (Krita), Treta, Dvapara and Kali. Each age is shorter than the one before, and dharma declines from four "legs" to one.

Hindu sources

• Manusmriti 1.68–86 gives the ages as 4,000, 3,000, 2,000 and 1,000 "divine years", plus twilights (sandhyas). That totals 12,000 divine years per Mahayuga.
• The Puranas (Vishnu Purana 1.3, among others) and the Mahabharata (Vana Parva 149, 188) count one divine year as 360 human years:
  • Satya 1,728,000 years; Treta 1,296,000; Dvapara 864,000; Kali 432,000. One Mahayuga is 4,320,000 years.
  • 1,000 Mahayugas make one Kalpa, a day of Brahma (4.32 billion years). 71 Mahayugas make a Manvantara.
• Classical astronomy (the Surya Siddhanta and Aryabhata, who wrote in 499 AD) dates the start of Kali Yuga to 18 February 3102 BCE (proleptic Julian calendar), tied to the death of Krishna. On this reckoning about 5,127 years of the Kali Yuga's 432,000 have passed by 2026.

Sri Yukteswar's 24,000-year cycle

Swami Sri Yukteswar Giri, in The Holy Science (1894), proposed that the divine-year multiplier was a later error.

• He described a 24,000-year cycle made of an ascending and a descending arc of 12,000 years each. Each arc has Satya 4,800, Treta 3,600, Dvapara 2,400 and Kali 1,200 years, twilights included.
• He linked the cycle to the Sun orbiting a "dual" star, an idea related to the precession of the equinoxes (about 25,772 years). Astronomy does not support this link.
• His dates: the descending arc ended with Kali at its lowest about 499 AD. The ascending Kali ran 499–1699 AD. The ascending Dvapara began about 1699, with its transition ending about 1899. On this view humanity is now rising towards Treta, which would begin about 4099 AD.
• Other modern reckonings exist, for example René Guénon's and Alain Daniélou's dates, and the Traditionalist reading that Kali ends around 2442 AD.

Helian reading

Tradition / belief The Helian Way equates the return of the Golden Age with the Return of Astraea.